what is watermarking and how its being used?

1. DIGITAL WATERMARKING
Sejal Visawadia

2. Watermark
What is Watermarking?
“ Watermarking can be considered as a special technique
of steganography where one message is embedded in
another and the two messages are related to each other in
some way. “
Example :The presence of specific patterns in currency
notes
which are visible only when the note is held to light is
a well known example for watermark.

3. Example of a conventional
watermark
Courtesy of Blue Spike, Inc.

4. Digital Watermark
“ Digital watermarking is similar to
watermarking physical objects, except that
the watermarking technique is used for
digital content instead of physical objects.”

5. Digital Watermark (Cont..)
In digital watermarking a low-energy signal is
imperceptibly embedded in another signal. The
low-energy signal is called watermark.
The main signal in which the watermark is
embedded is referred to as cover signal since
it covers the watermark.
An entity called watermark key used for
embedding and detecting watermark signal
Watermark key is private

6. Behind The Technology
Sending Side …
Watermark Embedding process

Water mark
 Original message
 Key

Water marked image

7. Behind The Technology
Receiving Side …
Watermark retrieval process


Water marked image
Key
 Confidential
message

8. The Overall System
The Technology Roars…

9. Importance Of
Digital Watermarking
© Copyright
Information
© On-line music industry
© News gathering using digital cameras

10. Types of Digital Watermarking





Robust & Fragile Watermarking
Visible & Invisible Watermarking
Public & Private Watermarking
Asymmetric & Symmetric
Watermarking
Steganograhic & NonSteganographic watermarking

11. Robust & Fragile
Watermarking

Robust Watermarking:-Modification of
watermarked content will not affect
watermark

Fragile Watermarking:-Watermark get
destroyed when watermarked content is
modified or tampered with

12. Visible & Invisible
Watermarking
 On Visible watermarking, contents are
visible

13. Visible & Invisible
Watermarking (Cont..)

Invisible watermarking are not viewed
on just looking

14. Public & Private
Watermarking
•
Public Watermarking
Users of content are authorized to detect
watermark
•
Private Watermarking
Users not authorized to detect watermark

15. Asymmetric & Symmetric
watermarking

In Asymmetric watermarking different
keys used for embedding and detecting
watermark

16. Asymmetric & Symmetric
watermarking (Cont..)

In symmetric watermarking same keys
are used for embedding and detecting
watermarks

17. Steganographic & NonSteganographic Watermarking

Steganographic Watermarking
User unaware of the presence of a
watermark
eg:-Used in finger printing
applications
 Non-Steganographic WM:User aware of the presence of a
watermark.
e.g.:-User to detect piracy

18. Digital Watermarking
Techniques
 LSB
Watermarking
 Color Separation Technique
 Bit Stream Watermarking
 Word Space Coding, Line Space
Coding &Character Coding

19. LSB Watermarking

Lower order bits of selected pixels in
the image are used to store watermarks

Replacing lower order bits of each
pixel with higher order bit of different image

20. Color Separation Technique

Watermark appears only in one of the
color bands

Used to watermark in still images

Can be extended to moving images

21. Bit Stream Watermarking

Used in audio watermarking

Data is directly inserted into compressed
audio files

22. Word Space Coding, Line Space
Coding & Character Coding

Used for watermarking in text documents

In word space coding, the spaces
between words are altered to embed
watermark code. In line space coding the
space between the lines are altered and in
character coding some of the characters
are imperceptibly modified (i.e., made
larger, serifs enhanced, etc).

23. Applications of Digital
Watermarking
Copy Protection
 Content Authentication
 Copyright Protection
 Metadata Tagging


24. Copy Protection

It limits the access to copyrighted material and
inhibit the copy process

25. Content Authentication
 Robust
watermarks are used in this area
Example:-A photographic information that
may be presented as evidence in court.
Since digital images can be easily
manipulated, there is a need to provide
proof that an image has not been altered.

26. Content Authentication

27. Copyright Protection
 One
of the main application
 Embedding
watermarks in digital
photographs

28. Metadata Tagging
 Watermarks
convey object specific
information to users of the object.
 Used
to attach patient identification data to
medical images, or to highlight regions of
diagnostic significance.

29. Attacks to Digital
Watermarking


Stirmark
Mosaic Attack

30. Stirmark




It is tool developed to test the robustness
of image marking system
Stirmark is commonly produced by
printers and scanners
IBM researchers have recently
announced a technique that defeats the
stir mark attack.
Detects and measures the geometric
distortions in images, and removes the
distortion to restore image geometry

31. Stirmark Example

32. Mosaic Attack
Use of a web crawler
 Dividing into sub images with rendition
instructions
 Browser will be rearranging the sub images
to appear as the original
 Sub images will be sufficiently small that no
single image on its own will contain a
recognizable mark.


33. Mosaic Attack Example

34. Conclusion

DRM systems and content management are
important for protection of rights of digital
multimedia creations that are distributed on the
Internet. Digital watermarking is an effective
technique for embedding rights information in
digital multimedia data.

Digital watermark technology can be used in
consumer electronic devices like digital still
camera, digital video camera, DVD players, MP3
players, etc., for various applications like providing
controlled access, preventing illegal replication and
watermark embedding

35. Conclusion (Contd..)

Digital information can easily be
disseminated and copied via global
networks.

The future of digital watermarking relies on
setting standards and creating applications
so that creators of digital content can easily
implement it.

36. THANK YOU